Messi has looked a frustrated figure over the last week, being held scoreless as Barcelona crashed out of the Champions League to Atletico Madrid, and then appeared to throw away their La Liga title chances with last Saturday’s 1-0 loss at Granada.

But Iniesta said the criticism Messi has received was a result of people having unrealistic expectations of the four-time Ballon d’Or winner, who he backed to bounce back quickly to top form.

“There are no doubts about Leo,” Iniesta said. “I cannot say anything else, nothing else comes to mind. In no moment would I ever doubt or be worried about him. He always tries to resolve games, to decide them. The bar has been set so high that it seems if he does not score twice he has not play well. But he is fundamental for us, and in a team game it is a question of everyone.”

Messi’s mental state is however a concern for former Argentina and Barcelona coach Cesar Luis Menotti, who told Catalan radio station La Xarxa, that the 26-year-old appeared to be suffering from a mental fatigue at the moment.

“[Messi] has to overcome his sadness at bad results and play with a smile, with pride and with the passion that you need to play for a club like Barcelona, he must get that back,” Menotti said. “I have seen him with a certain mental fatigue, more than physical tiredness. It is normal because there have been so many games, he has a lot of obligations. Maybe with a few days of relaxing he can get his head straight again and be the best in the world as he is.”

But Menotti denied that his countryman was holding anything back ahead of the summer’s World Cup finals.

“I do not believe he is reserving anything for Brazil, I believe there is a certain disorder in his head, it is not clear,” the 1978 World Cup-winning manager said. “That has happened to the best players in the world. But I trust a lot in his quality and believe that tomorrow for sure he will play a great game and get things straight again. He is always very generous. I do not believe it has anything to do with the World Cup. Everyone has days when things do not go as we want. We must help him to get his best form back.”

Messi’s demeanour has been seized upon as a positive in the Spanish capital, given that the Blaugrana player has 21 goals in 27 career clasicos, including three in last month’s 4-3 La Liga win at the Estadio Santiago Bernabeu.

Real Madrid captain Iker Casillas told his pregame news conference that he was not bothering to think about his long-time nemesis’ form ahead of the game, and did not anyway trust stories of Barca’s demise.

“I am not concerned about how Messi is, I am concerned with my own team,” Casillas said. “I would not be taking anything from Barcelona’s last week. This is totally different, a final, and anything could happen. This final can bring their first big trophy of the season. We are playing well ourselves. We must forget what has happened before, what might happen in future, and look at what will happen tomorrow.”